Naming Compounds Writing Formulas

Systematic Naming l There are too many compounds to remember the names of them all. l Compound is made of two or more elements. l Put together atoms. l Name should tell us how many and what type of atoms.

Periodic Table l More than a list of elements. l Put in columns because of similar properties. l Each column is called a group.

2A 1A 3A4A 5A 6A 7A 0 Representative elements l The group A elements

Metals

l Luster – shiny. l Ductile – drawn into wires. l Malleable – hammered into sheets. l Conductors of heat and electricity.

Transition metals l The Group B elements

Non-metals l Dull l Brittle l Nonconductors - insulators

Metalloids or Semimetals l Properties of both l Semiconductors

Atoms and ions l Atoms are electrically neutral. l Same number of protons and electrons. l Ions are atoms, or groups of atoms, with a charge. l Different numbers of protons and electrons. l Only electrons can move. l Gain or lose electrons.

Anion l A negative ion. l Has gained electrons. l Non metals can gain electrons. l Charge is written as a super script on the right. F -1 Has gained one electron O -2 Has gained two electrons

Cations l Positive ions. l Formed by losing electrons. l More protons than electrons. l Metals form cations. K +1 Has lost one electron Ca +2 Has lost two electrons

Compounds l Follow the Law of Definite Proportion. l Have a constant composition. l Have to add the same number of atoms every time. l Two types.

Two Types of Compounds  Molecular compounds l Made of molecules. l Made by joining nonmetal atoms together into molecules.

Two Types of Compounds  Ionic Compounds l Made of cations and anions. l Metals and nonmetals. l The electrons lost by the cation are gained by the anion. l The cation and anions surround each other. l Smallest piece is a FORMULA UNIT.

Two Types of Compounds Smallest piece Melting Point State Types of elements Formula UnitMolecule Metal and Nonmetal Nonmetals solid Solid, liquid or gas High >300ºCLow <300ºC IonicMolecular

Chemical Formulas l Shows the kind and number of atoms in the smallest piece of a substance. l Molecular formula- number and kinds of atoms in a molecule. l CO 2 l C 6 H 12 O 6

Formula Unit l The smallest whole number ratio of atoms in an ionic compound. l Ions surround each other so you can’t say which is hooked to which. (pg 91)

Charges on ions l For most of the Group A elements, the Periodic Table can tell what kind of ion they will form from their location. l Elements in the same group have similar properties. l Including the charge when they are ions.

What about the others? l We have to figure those out some other way. l More on this later.

Naming ions l We will use the systematic way. l Cation- if the charge is always the same (Group A) just write the name of the metal. l Transition metals can have more than one type of charge. l Indicate the charge with roman numerals in parenthesis.

Name these l Na +1 l Ca +2 l Al +3 l Fe +3 l Fe +2 l Pb +2 l Li +1

Write Formulas for these l Potassium ion l Magnesium ion l Copper (II) ion l Chromium (VI) ion l Barium ion l Mercury (II) ion

Naming Anions l Anions are always the same. l Change the element ending to – ide l F -1 Fluorine

Naming Anions l Anions are always the same l Change the element ending to – ide l F -1 Fluoride

Name these l Cl -1 l N -3 l Br -1 l O -2 l Ga +3

Write these l Sulfide ion l iodide ion l phosphide ion l Strontium ion

Polyatomic ions l Groups of atoms that stay together and have a charge. l You must memorize these. l Acetate C 2 H 3 O 2 -1 l Nitrate NO 3 -1 l Nitrite NO 2 -1 l Hydroxide OH -1 l Permanganate MnO 4 -1 l Cyanide CN -1

Polyatomic ions l Sulfate SO 4 -2 l Sulfite SO 3 -2 l Carbonate CO 3 -2 l Chromate CrO 4 -2 l Dichromate Cr 2 O 7 -2 l Phosphate PO 4 -3 l Phosphite PO 3 -3 l Ammonium NH 4 +1

Ions in Ionic Compounds

Naming Binary Ionic Compounds l Binary Compounds - 2 elements. l Ionic - a cation and an anion. l To write the names just name the two ions. l Easy with Representative elements. l Group A l NaCl = Na + Cl - = sodium chloride l MgBr 2 = Mg +2 Br - = magnesium bromide

Naming Binary Ionic Compounds l The problem comes with the transition metals. l Need to figure out their charges. l The compound must be neutral. l same number of + and – charges. l Use the anion to determine the charge on the positive ion.

Naming Binary Ionic Compounds l Write the name of CuO l Need the charge of Cu l O is -2 l copper must be +2 l Copper (II) chloride l Name CoCl 3 l Cl is -1 and there are three of them = -3 l Co must be +3 Cobalt (III) chloride

Naming Binary Ionic Compounds l Write the name of Cu 2 S. l Since S is -2, the Cu 2 must be +2, so each one is +1. l copper (I) sulfide l Fe 2 O 3 l Each O is -2 3 x -2 = -6 l 3 Fe must = +6, so each is +2. l iron (III) oxide

Naming Binary Ionic Compounds l Write the names of the following l KCl l Na 3 N l CrN l Sc 3 P 2 l PbO l PbO 2 l Na 2 Se

Ternary Ionic Compounds l Will have polyatomic ions l At least three elements l name the ions l NaNO 3 l CaSO 4 l CuSO 3 l (NH 4 ) 2 O

Ternary Ionic Compounds l LiCN l Fe(OH) 3 l (NH 4 ) 2 CO 3 l NiPO 4

Writing Formulas l The charges have to add up to zero. l Get charges on pieces. l Cations from name of table. l Anions from table or polyatomic. l Balance the charges by adding subscripts. l Put polyatomics in parenthesis.

Writing Formulas l Write the formula for calcium chloride. l Calcium is Ca +2 l Chloride is Cl -1 l Ca +2 Cl -1 would have a +1 charge. l Need another Cl -1 l Ca +2 Cl 2 -1

Write the formulas for these l Lithium sulfide l tin (II) oxide l tin (IV) oxide l Magnesium fluoride l Copper (II) sulfate l Iron (III) phosphide l gallium nitrate l Iron (III) sulfide

Write the formulas for these l Ammonium chloride l ammonium sulfide l barium nitrate

Things to look for l If cations have (), the number is their charge. l If anions end in -ide they are probably off the periodic table (Monoatomic) l If anion ends in -ate or -ite it is polyatomic

Molecular Compounds Writing names and Formulas

Molecular compounds l made of just nonmetals l smallest piece is a molecule l can’t be held together because of opposite charges. l can’t use charges to figure out how many of each atom

Easier l Ionic compounds use charges to determine how many of each. –Have to figure out charges. –Have to figure out numbers. l Molecular compounds name tells you the number of atoms. l Uses prefixes to tell you the number

Prefixes l 1 mono- l 2 di- l 3 tri- l 4 tetra- l 5 penta- l 6 hexa- l 7 hepta- l 8 octa-

Prefixes l 9 nona- l 10 deca- l To write the name write two words

Prefixes l 9 nona- l 10 deca- l To write the name write two words l One exception is we don’t write mono- if there is only one of the first element. l No double vowels when writing names (oa oo) PrefixnamePrefixname-ide

Name These lN2OlN2O l NO 2 l Cl 2 O 7 l CBr 4 l CO 2 l BaCl 2

Write formulas for these l diphosphorus pentoxide l tetraiodide nonoxide l sulfur hexaflouride l nitrogen trioxide l Carbon tetrahydride l phosphorus trifluoride l aluminum chloride

Acids Writing names and Formulas

Acids l Compounds that give off hydrogen ions when dissolved in water. l Must have H in them. l will always be some H next to an anion. l The anion determines the name.

Naming acids l If the anion attached to hydrogen is ends in -ide, put the prefix hydro- and change -ide to -ic acid l HCl - hydrogen ion and chloride ion l hydrochloric acid l H 2 S hydrogen ion and sulfide ion l hydrosulfuric acid

Naming Acids l If the anion has oxygen in it l it ends in -ate of -ite l change the suffix -ate to -ic acid l HNO 3 Hydrogen and nitrate ions l Nitric acid l change the suffix -ite to -ous acid l HNO 2 Hydrogen and nitrite ions l Nitrous acid

Name these l HF lH3PlH3P l H 2 SO 4 l H 2 SO 3 l HCN l H 2 CrO 4

Writing Formulas l Hydrogen will always be first l name will tell you the anion l make the charges cancel out. l Starts with hydro- no oxygen, -ide l no hydro, -ate comes from -ic, -ite comes from -ous

Write formulas for these l hydroiodic acid l acetic acid l carbonic acid l phosphorous acid l hydrobromic acid